Respuesta :

Answer:

D) cos^-1 (f/e)

Step-by-step explanation:

Since you only know two sides, DE = f, and DF = e, you need to use cosine to find the measure of ∠D.

Let x represent m∠D

cos x = f/e

To find x, take the inverse of cos, so:

cos^-1 (f/e) = x